Cracking the DNA mixture code – computer analysis of UK crime cases Forensics Europe Expo Forensic Innovation Conference April, 2014 London, UK Mark W Perlin, PhD, MD, PhD Cybergenetics, Pittsburgh, PA Cybergenetics ©

Leicestershire bank robbery

Black balaclava

Brown parka

Black shoes

Helicopter view Bank House Lutterworth Broughton Astley

Brown parka

Black balaclava

Black shoes

DNA biology Locus Chromosome Nucleus Cell

Short tandem repeat It was the best of times, it was the worst of times, it was the age of wisdom, it was the age of foolishness, it was the epoch of belief, it was the epoch of incredulity, it was the season of Light, it was the season of Darkness, it was the spring of hope, it was the winter of despair, we had everything before us, we had nothing before us, we were all going direct to Heaven, we were all going direct the other way -- in short short short short short short short short short short, the period was so far like the present period, that some of its noisiest authorities insisted on its being received, for good or for evil, in the superlative degree of comparison only. "short" repeated 10 times, so allele length is 10 repeats 23 volumes in cell's DNA encyclopedia DNA locus paragraph

DNA genotype 10, ACGT A genetic locus has two DNA sentences, one from each parent. locus Many alleles allow for many many allele pairs. A person's genotype is relatively unique. mother allele father allele repeated word An allele is the number of repeated words. A genotype at a locus is a pair of alleles

DNA evidence interpretation Evidence item Evidence data LabInfer Evidence genotype Known genotype 10, 50% 11, 30% 12, 20% 10, 12 Compare

Informative peak height pattern Quantitative peak heights from parka at locus TH01 peak height peak size

People may use less of the data Threshold Over threshold, peaks are labeled as allele events All-or-none allele peaks, each given equal status Under threshold, alleles vanish

DNA lab report: Balaclava A sample from the inside crown area of the balaclava (item JAS/3) was submitted for DNA profiling tests. A complex mixed DNA results which appeared to have originated from at least four people was obtained from biological material on the crown. In my opinion, this result is not suitable for meaningful comparison.

DNA lab report: Shoes The inside heel area and the toe area of the left shoe (item PAC/2) were submitted separately for DNA profiling tests. Mixed DNA results which appeared to have originated from at least three people were obtained from biological material on each of the sampled areas. In my opinion, Leroy Williams could have contributed DNA to these results in that all of the components that make up his DNA profile are represented in the result; however, due to the overall complexity of the results and the number of contributors to them, a statistical evaluation is not possible.

DNA lab report: Parka The left and right cuff areas of the brown parka (item CEG/2) were submitted separately for DNA profiling tests. A complex mixed DNA results which appeared to have originated from at least four people was obtained from biological material on the right cuff. In my opinion, this result is not suitable for meaningful comparison. A mixed DNA result, which appeared to have originated from at least three people was obtained from biological material recovered from the left cuff of the brown parka (CEG/2). In my opinion Leroy Williams could have contributed DNA to this result; however, the finding is not suitable for statistical evaluation.

How the computer thinks Consider every possible genotype solution Explain the peak pattern Better explanation has a higher likelihood Allele pair from one person Another person's allele pair A third person's allele pair

Objective genotype determined solely from the DNA data. Never sees a comparison reference. Evidence genotype 99.98% 0.01%

DNA match information Prob(evidence match) Prob(coincidental match) How much more does the suspect match the evidence than a random person? 10x 99.98% 11%

Match information at 10 loci

Is the suspect in the evidence? A match between the parka and Leroy Williams is: 10.2 quadrillion times more probable than a coincidental match to an unrelated Black person A match between the shoe and Leroy Williams is: 13.9 quadrillion times more probable than a coincidental match to an unrelated Black person A match between the balaclava and Leroy Williams is: 15.7 quadrillion times more probable than a coincidental match to an unrelated Black person 10,000,000,000,000,000

The TrueAllele option Objective, reliable truth-seeking tool solves the DNA mixture problem relatives & up to six contributors handles low-copy and degraded DNA provides accurate DNA match statistics easy to understand, easy to explain automates DNA evidence interpretation When a report says "a meaningful comparison" or "a statistical evaluation” is not possible, TrueAllele is often highly effective.

Reliable: validation studies Perlin MW, Sinelnikov A. An information gap in DNA evidence interpretation. PLoS ONE. 2009;4(12):e8327. Perlin MW, Legler MM, Spencer CE, Smith JL, Allan WP, Belrose JL, Duceman BW. Validating TrueAllele ® DNA mixture interpretation. Journal of Forensic Sciences. 2011;56(6): Ballantyne J, Hanson EK, Perlin MW. DNA mixture genotyping by probabilistic computer interpretation of binomially-sampled laser captured cell populations: Combining quantitative data for greater identification information. Science & Justice. 2013;53(2): Perlin MW, Belrose JL, Duceman BW. New York State TrueAllele ® Casework validation study. Journal of Forensic Sciences. 2013;58(6): Perlin MW, Dormer K, Hornyak J, Schiermeier-Wood L, Greenspoon S. TrueAllele ® Casework on Virginia DNA mixture evidence: computer and manual interpretation in 72 reported criminal cases. PLOS ONE. 2014:9(3)e92837.

TrueAllele in criminal trials Court testimony: state federal military international About 200 case reports filed on DNA evidence Crimes: armed robbery child abduction child molestation murder rape terrorism weapons

United Kingdom & Commonweath countries Country Australia (1) Canada (3) England (8) Northern Ireland (10) Crime Armed robbery (1) Identify theft (1) Murder (14) Rape (2) Terror (4) TrueAllele has analyzed 22 cases

TrueAllele today Invented math & algorithms20 years Developed computer systems15 years Support users and workflow10 laboratories Used routinely in casework3 labs Validate system reliability20 studies Educate the community50 talks Train & certify analysts200 students Go to court for admissibility5 hearings Testify about LR results20 trials Educate lawyers and laymen1,000 people Make the ideas understandable200 reports

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